Final answer:
The most specific word to replace 'buildings' when referring to impressive structures that touch the sky is 'skyscrapers'. Skyscrapers represent the pinnacle of urban architecture and are made possible by steel frameworks and elevators.
Step-by-step explanation:
The best replacement for the word "buildings" in the given context would be skyscrapers. This term specifically refers to very tall, continuously habitable buildings that have a significant height and can often seem to touch the sky, which is exactly the impression that is described.
The development and proliferation of skyscrapers were facilitated by advancements in steel girder construction, the invention of passenger and freight elevators, and the high value of urban real estate. Notable for their awe-inspiring height, skyscrapers dominate city skylines, often symbolizing economic power and architectural progress. Examples include iconic structures like the Home Insurance Building in Chicago, often referred to as the world's first skyscraper, and the Woolworth Building in New York, a classic example of early 20th-century skyscraper design.